CT2577 Aeroflex Circuit Technology, CT2577 Datasheet - Page 16

• Manufacturer Part Number: CT2577
• Description: APPLICATION NOTE #108
• Manufacturer: Aeroflex Circuit Technology

RETRIEVING OR LOADING DATA TO RAM
APPLICATION NOTE #108
DATA STORAGE AND RETRIEVAL IN RAM
The storage and retrieval of data on RAM is optimized for fast processor accesses. The
data (Transmit or Receive) is stored with the first data word (Word #0) in memory location
#0n and the last data word (Word #n) in location 00. The processor reads the Command
word and extracts the T/R bit, subaddress, and word count bits as a pointer to the proper
memory location. The word count field is used as a down counter variable so that a Do Loop
routine is executed and then branched out at counter = 00. This may be more efficient in
some compilers than an up counter and comparing current loop counter with word count
field on every loop. The following section contains sample software pseudo code for data
handling. See Memory Map for further details.
SAMPLE SOFTWARE CODE
The following section contains sample pseudo-code for programming and operation the
SmaRT unit. The code most resembles Microsoft Quick Basic code (IBM DOS compatible)
for simplicity.
REM ********************************************************************************************
REM ********************************************************************************************
REM *
REM *
REM *
REM *
REM *
REM *
REM *
REM *
REM *
REM *
REM *
REM *
REM *
REM *
REM *******************************************************************************************
REM *
REM *
REM *
REM *
REM *
REM *
REM *
REM *
REM *
REM *
REM *
REM *
REM *
Variables
CMDWORD = COMMAND WORD READ FROM FIFO
WORDCNT = LOWER 5 BIT OF COMMAND WORD
_______
MODE
NCMDEMPTY
DATA() = DATA ARRAY (32 WORDS MAX)
MEMPOINT = LOWER 11 BITS OF THE COMMAND WORD
T/R_BIT = BIT #10 OF THE COMMAND WORD
Routines for operation in Remote Terminal (RT) Mode
INDICATES HOW MANY DATA WORDS
0 = EMPTY (NO Command WORDS IN FIFO)
0 = RT MODE
on the CT2577.
1 = HAVE COMMAND WORDS IN FIFO
This signal is derived from NEMPTY
1 = BC MODE
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Released 9/98